The strong quake that struck south-west of Bulgaria's capital Sofia early on Tuesday made no casualties thanks to heavenly protection, a local clergyman claims.

Bishop Joan has suggested that the relics of Saint Ivan Rilski, part of which are housed by the temple at the quake-hardest hit town of Pernik, are working miracles.

"A particle of the relics of St. Ivan Rilski, which was transferred in 2009 from St. Rila monastery to the central temple in Pernik, preserved this town and the lives of its people," said Bishop John Znepolski at a mass that he held in Pernik.

He urged the people not to mourn the material damages the earthquake left in its wake on May 22 because there is nothing more precious than human life.

"St. Ivan Rilski has been protecting Bulgaria more than 1,000 years already," said the bishop.

Tuesday's initial earthquake had a magnitude of about 5.8-5.9 on the Richter scale and struck at 2:58 am. Its epicenter was about 6 km from Pernik and approximately 25 km from the capital Sofia.

Researchers from the Bulgarian Academy of Sciences have explained that aftershocks may reach a magnitude of 4 on the Richter scale, which would not damage the infrastructure. However, objects may fall and injuries may occur.

Saint Ivan Rilski, known as the Miracle Worker, is revered as the patron of Bulgaria.

He founded the Rila Monastery some 1,000 years ago. The saint's relics are kept there to this day, and are still believed to have the power to bring miracle cures for illnesses.

Hundreds of pilgrims gather every year on October 19 in Bulgaria's biggest cloister, the Rila Monastery, to mark the holiday. People queue to touch the relics of the saint, hoping he would bring miracles to their  lives too.

St. Ivan Rilski died in 946 AD in the seclusion of the monastery, and was canonized right after his death. Remembered for his miracles, he is one of Bulgaria's most influential spiritual leaders.

Shortly after the saint's death, his remains, which were thought to have wonder-working powers, were transferred to Sofia during the reign of Peter I. After Magyar King B?la III conquered Sofia in 1183, Saint Ivan Rilski's remains were sent to the Hungarian capital Esztergom and stayed there for 4 years before being returned to Sofia in 1187.

In 1194, Bulgarian Tsar Ivan Asen I ordered the remains to be moved to his capital, Veliko Tarnovo. Surviving the Turkish conquest of the city in 1393, they were returned to the Rila Monastery in 1469 with the permission of Sultan Murad II.